445 dates and irregularities
Manufacturing and retail companies often use a special type of calendar, which ensures that all months have an equal number of days. This is commonly called a 445 calendar, which indicates that a month is made of 4 weeks, with the next month comprising 4 weeks, and the final month (in the quarter) comprising of 5 weeks. The next quarter follows the same pattern of 2 x 4 weeks and then a 5-week month.
Month names in the 445 calendar do not always equate to the calendar month. The 445 calendar month of January may run into February, and December may run into January (in fact this is frequently the case). Further, the week can start on any day of the calendar week, and a 445 calendar's month never end on the same calendar day of a month.
Although there are variations of this pattern (454 and 544), the concepts and implications of the calendar are the same. It poses a challenge in the model because a year does not start or end on the same date, and the months do not...
